When discussing Aikido and it's benefits for dissipating violence, we could separate the training process itself and the application of Aikido in a self defense situation.

Aikido training, if practices in a non-impositional and cooperative manner, cultivates in a person the willingness to walk away from a fight. We could debate what O Sensei would have thought about violence and mercy. He was a strict vegetarian. There is good reason to believe, meaning loads of information to indicate, that he wanted to change his ways after the war. I think Graham is describing the highest ideal that O Sensei encouraged us to strive towards. So the training process itself dissipates violence in us if we let it.

As to the application to self defense things get tricky. You could strive to avoid any harm to an attacker. If you were unable to defend yourself without harming the attacker you could allow the attacker to harm you. That is an ethical choice. If you aren't willing to sacrifice injury for your ideals, then you could strive to minimize harm to the attacker. Often times an attack my place an attacker in a very dangerous situation. You simply blend at the right time and the attacker flies head first into a object that seriously injures or kills him. In such a situation you can attempt to prevent this by protecting the attacker but it is still possible that you will fail in your efforts. Even a controlling technique like ikyo and pen can result in injuries. Even minor injuries like scrapes can occur if nothing else.

Having said this I am not sure, Graham, if you consider it violence if an attacker hurts himself from the attack.

I certainly agree that Aikido works as an art when you don't try to impose. I also agree that Aikido training can be a way to work the violence, and other things, out of ourselves. I can accept the idea that it is violence when you use Aikido to harm an attacker. Even if that's all you could do to protect yourself, it could still be considered necessary but unfortunate violence. We are talking about ideals. The goal should be that there is no injury to anyone. In practice, however, it may be impossible to protect Uke from his own violence or to defend yourself without resorting to violence. Are you saying something different?